Roof supports for mine workings



Jam 20, 1970 K. M- GRQETSCHEL ROOF SUPPORTS FOR MINE WORKINGS Filed Nov. 14, 1967 12 Sheets-Sheet 1 eas Jm. 20, 1970 K. M GROETSCHEL ROOF SUPPORTS FOR MINE WORKINGS 12 Sheets-Sheet 2 Filed NOV. 14, 1967 Jan. 20, 1970 K. M. GROETSCHEL 3,490,243

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ROOF SUPPORTS FOR MINE WORKINGS l2 Sheets-Sheet 11 Filed Nov. 14, 1967 Jan. 20, 1970 K. M. GROETSCHEL 3,490,243

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United States Patent 3,490,243 ROOF SUPPORTS FOR MINE WORKINGS Karl Maria Groetschel, 44 Stalzestrasse,

463 Bochum, Germany Filed Nov. 14, 1967, Ser. No. 682,867 Claims priority, application Germany, Nov. 16, 1966, G 48,476; Mar. 15, 1967, G 49,571 Int. Cl. E21d 23/20 US. Cl. 61-45 34 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a roof support for a mine working which includes a top structure and a bottom structure each sub-divided into an inner part and an outer part interleaved laterally with each other with the inner part in each case able to move angularly relatively to the outer part in a plane parallel to the fioor'and roof, the top structure being carried by hydraulic props mounted on the bottom structure, and the angular relation between the inner part and the outer part of the bottom structure or both structures being determined by guide devices engaged between the inner and outer parts at longitudinally spaced positions. One of such guide devices is adjustable and preferably comprises a power-operatedlaterally shiftable element mounted on the inner part and having faces contacting opposed laterally presented faces of the outer part of the structure.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to roof supports primarily for use in underground mine workings of the kind comprising a bottom structure for resting on the floor, a top structure for engaging and supporting the roof, a plurality of poweroperated extensible props extending between the top and bottom structures, and traction means for advancing the support. Such supports are hereinafter referred to as being of the kind specified.

Self-advancing roof supports of the kind specified are ordinarily employed in a system of coal-mining known as long wall mining wherein a plurality of the supports are disposed at positions spaced apart laterally from each other along the length of the coal face, and a conveyor and coal-getting machinery is advanced periodically towards newly exposed portions of the coalface as coal is extracted therefrom by movement of the coal-getting machinery along the coal face, the traction means of the supports being operated to move the supports in succession towards the coal face.

In many mines the fioor (and roof) of the mine working is inclined to the horizontal in a direction from one of the coal face towards the other, and there is often a tendency for an individual roof support to be displaced out of its proper laterally spaced relationship with the adjacent roof supports on each side of it, or for the whole of a group of successive roof supports to slide in the downward direction in which the floor of the mine working slopes.

One of the objects of the present invention is to ensure that individual roof supports can be advanced in the required direction towards the coal face without becoming displaced downwardly in a direction in which the floor of the mine working slopes laterally.

Description of the prior art In my prior Patent No. 3,320,751 I have described and claimed a self-advancing roof support comprising a plurality of power-operated extensible props mounted on a base, and a roof engaging superstructure carried by the Patented Jan. 20, 1970 props, the support including a part which can be projected forwardly relatively to the remaining part by poweroperated traction means, and including guide means for determining the direction of such projection relatively to a horizontal longitudinally extending reference axis of the support, such guide means having co-operative parts disposed respectively on said forwardly projectible part and on said remaining part of the support and defining predetermined paths diverging respectively to the left and to the right with respect to the reference axis, the guide means and traction means being operable to project said part selectively along a path parallel to the reference axis or along one or the other of said divergent paths.

In the specific embodiments disclosed in this prior patent the base of the support comprised a rearward base element and a forward base element (the latter forming the forwardly projectible part mentioned in the preceding paragraph) and the guide means comprised laterally displaceable slides situated at longitudinally spaced positions on the rear base element and having apertures receiving a longitudinally extending guide plate fixedly connected to the forward base element so that, by appropriately adjusting the position of the slides, the path of movement along which the forward base element could be advanced was determined.

My co-pending application 690,856 filed Dec. 15, 1967 divided from my application 392,002 now issued as United States Letters Patent 3,371,901 relates to roof supports primarily for use in underground mine workings and is concerned with a roof support comprising a base, a plurality of power-operated extensible props carried thereon, a roof engaging superstructure, and traction means for advancing the support. I have described therein and claimed such a self-advancing roof support wherein the superstructure comprises two parts which are interleaved with each other but have mutual clearance laterally of the direction of advancement, and one of which projects forwardly of the other upon its advancement by the traction means, and wherein the lateral position and path of advancement of the forwardly projecting part relatively to a reference axis extending medially and longitudinally of the support is determined within the limits afforded by said mutual clearance by guide means disposed at the level of the superstructure, such guide means being adjustable to vary the angular relationship in a plane parallel to the roof between said path and said reference axis.

In the specific embodiment disclosed in my co-pending application 690,856 the guide means disposed at the level of the superstructure comprised a single guide memher in the form of a cradle or trough which lay between lateral boundaries of a channel afforded by a rear part of the superstructure, such cradle or trough slidably receiving the rear portion of the fore part of the superstructure and itself being angularly movable about a substantial vertical axis by means of a pin connecting the trough or cradle to a horizontally angularly movable crosshead disposed in the base of the support. 1

Further, my co-pending application 701,138 filed Jan.

29, 1968 divided from my application 544,145 now issued as United States Letters Patent 3,399,927 is concerned with a roof support primarily for use in underground mine' by the traction means, one of these parts of the superstructure being so supported from its associated prop or props so as to be capable of angular movement in a plane parallel to the floor of the Working within the limits afforded by said mutual clearance, and wherein the angular position and path of advancement of each part of the superstructure relative to a horizontal, longitudinally extending, reference axis of the support was determined by guide means disposed at the level of the superstructure and comprising at least one adjustable guide element situated at a position spaced longitudinally of the superstructure from the axis about which said angular movement can take place.

In the specific embodiment disclosed the axis about which said angular movement can take place was defined by one of the props carried by the base, and the guide element included plungers extending laterally outwardly from the inner part of the superstructure for engagement with the laterally inwardly presented face of outer faces of the superstructure, such plungers being urged outward- 1y by spring means or held positively in adjusted positions by clamping means, or displaced laterally by hydraulic piston and cylinder units to effect angular movement of the inner part of the superstructure about said axis.

Whilst all these foregoing arrangements provided in each case a substantial measure of improvement as to the control of direction of advancement of the roof support more especially in mine workings wherein the floor (and roof) slope laterally of the support, that is to say in the direction of the length of the coal face when mining is conducted in accordance with the method of long wall coal mining currently in use, conditions can arise in which even these arrangements do not provide control as ,to the direction of advancement to the extent necessary to ensure that each roof support remains, over an extended period of use, in its proper position in a row of such supports extending along the coal face.

The object of the present invention is to provide improved means for guiding and steering the support along a path of advancement.

SUMMARY OF THE INVENTION According to the present invention a support for supporting the roof of a mine working comprises a bottom strui'cture for resting on the fioor, a top structure for engaging and supporting the roof, a plurality of powerope'rated extensible props extending between said top and bottom structures, traction means for advancing said support, and includes the improvement wherein at least one of said structures includes longitudinally extending parts eacli having at least two longitudinally spaced seatings engaged by respective ones of said props, said parts are disposed in interleaved relation With each other in a direction laterally of the support, said parts are laterally spaced from each other to define inter-part clearance spaces providing the capability of relative angular movement between said parts in a plane generally parallel to said floor and roof, guide means are provided for controlling the relative angular positions of said parts in said plane, said guide means including a first guide device operatively engaged between said parts at a first position therealong, a second guide device operatively engaged between said parts'at a second position therealong spaced longitudinally from said first posiiton, at least one of said guide devices including means enabling the relative angular positions of said parts to be adjusted.

Embodiments of the invention will now be described with reference to the accompanying drawings wherein:

FIGURES 1 to 4 are diagrammatic plan views of one of the structures of a roof support of the kind specified provided with guide devices in accordance with the invention;

FIGURE 5 is a view in side elevation and in crosssection on the line 5-5 of FIGURE 7 of a first embodi- 4 ment of roof support in accordance with the invention;

FIGURE 6 is a plan view of the first embodiment in cross-section on the line 6-6 of FIGURE 5;

FIGURE 6A is a fragmentary view in side elevation and in crpss-section on the line 6A,6A of FIGURE 6 showing the provision of one of the stabilising elements on a sidemember of the bottom structure for stabilising the inner part of the bottom structure and props and top structure carried thereby against lateral deflection;

FIGURE 7 is a view in end elevation of the first embodiment on the line 77 of FIGURE 5;

FIGURE 7A is a fragmentary view in rear elevation showing the bottom structure of the first embodiment and in particular the laterally disposed transversely slidable plate incorporated in the adjustable guiding device at the rearend;

FIGURE 8 is a plan view of a second embodiment of a roof support of the kind specified in accordance with the invention, the top structure being omitted;

FIGURE 9 is a view in side elevation of the second embodiment;

FIGURE 10 is a view in end elevation and in crosssection on the line 1010 of FIGURE 9;

FIGURE 11 is a plan view of a third embodiment of roof suppport of the kind specified in accordance with the invention, the top structure being omitted;

FIGURE 12 is a fragmentary plan view on an enlarged scale of the adjustable guide device incorporated in the embodiment of FIGURE 11 but shown reversed left to right relative to the showing of FIGURE 11;

FIGURE 13 is a fragmentary view in side elevation of the guide device shown in FIGURE 12;

FIGURE 14 is a fragmentary view in end elevation and in cross-section on the line 1414 of FIGURE 11;

FIGURE 15 is a View in end elevation and partly in vertical cross-section of a fourth embodiment of roof support of the kind specified in accordance with the invention generally similar to the third embodiment but incorporating longitudinally spaced guide devices in the top structure as well as in the bottom structure;

FIGURE 16 is a view in side elevation of a fifth embodiment of roof support of the kind specified in accordance with the invention incorporating two adjustable guide devices in both the bottom structure and the top structure;

FIGURE 17 is a diagrammatic view in plan, and partly in vertical cross-section, of one arrangement of adjustable guide device which may be incorporated in any of the foregoing embodiments of roof support;

FIGURE 18 is a view in side elevation of a sixth embodiment of roof support of the kind specified in accordance with the invention partly in vertical cross-section;

FIGURE 19 is a plan view of the sixth embodiment, the top structure being removed;

FIGURE 20 is a plan view of a seventh embodiment, the top structure of the support being removed and the adjustable guide device incorporating a longitudinally movable element shown in its extended position; and

FIGURE 21 is a view similar to FIGURE 20 with the longitudinally movable element in its retracted position in consequence of the outer base element having been advanced.

Referring firstly to the diagrammatic drawings FIG- URES 1 to 4, these illustrate in principle various alternative forms of guiding means which may be adopted within the scope of the invention.

Each of FIGURES 1 to 4 illustrates the application of guiding means to either the bottom structure or the top structure of a roof support of the kind specified. In each case the structure includes interleaved parts, one of which, herein called the outer part, is designated A and the other of which, herein called the inner part, is desig nated B, the latter having clearance space between its outer side faces and the inwardly presented side faces of the outer part A. The two side members of he outer part A are connected to each other at opposite ends in a rigid manner and either part A or B is capable of angular movement in a plane parallel to the floor or roof of the working for the purpose of controlling the direction of advancement, is indicated by the arrow C.

Each part is advanced in succession by the traction means of the support while the props, including at least two longitudinally spaced props, are relieved to effect lowering of the top structure from the roof or at least relaxation of the pressure exerted against the latter, and whilst the other part is maintained in load-bearing relation with the roof by full pressurisation of its props which again include two longitudinally spaced props.

In the arrangement shown in FIGURE 1 the direction of advancement is indicated by the arrow C. In this case two longitudinally spaced guide devices are provided to control the direction of advancement, one such guide device includes fixed guide elements W and an adjustable guide element K, the former being mounted on, and projecting inwardly from, the side members of the part A of the structure, and the latter being mounted on, but shiftable laterally with respect to, the part B of the structure. Clearance spaces sufiicient to prevent binding or jamming exist between the guide elements W and the inner part B of the structure.

In the alternative arrangement illustrated in FIGURE 2 components corresponding to those already described are designated by like numerals of reference.

In this case the fixed guide elements W are provided on the inner part B and the adjustable guide device K incorporating the laterally shiftable element is also mounted on the part B. The clearance spaces between the fixed guide elements W in this case can be made somewhat less than those shown in FIGURE 1.

In the arrangement of FIGURE 3 components corresponding to those already described are designated by like numerals of reference. In this case both guide devices are of the adjustable kind K each incorporating a laterally shiftable guide element and both are mounted on the part B of the structure.

In the arrangement of FIGURE 4 wherein again parts corresponding to those already described are designated by like numerals of reference, the fixed guide elements W are mounted on the part B of the structure and the adjustable guide device K incorporates a laterally shiftable element K which is moved through the intermediary of a mechanism such as a lever L pivoting about an axis M and movable in opposite directions, as indicated by the arrow N, either manually or by a power energised actuating means, for example a piston and cylinder assembly.

In each of the arrangement illustrated in FIGURES 2, 3 and 4 the direction of advancement of the part B is determined by the angular relationship which the inwardly presented side faces of the side members of the part A bear to a reference axis P. These side faces as shown are parallel to the reference axis but can be caused to take up an acute angled relation thereto by operation of the adjustable guide device K (or each of the adjustable guide devices K in opposite directions when using the arrangement of FIGURE 3) when the props associated with the part A of the superstructure are released so that this part is free to move angularly in a plane parallel to the floor and roof relative to the part B held in a fixed position, by virtue of pressurisation of its associated props. Such angular movement of the part A may be accomplished prior to advancement of the part B in the direction of the arrow C or at the end of the advancement step. In the former case the part B will then advance along a path which diverges to the left or to the right of the reference axis P. In the latter case the part B will advance along the reference axis or parallel thereto but the follow-up movement imparted to the part B will then take place along one or the other of said divergent paths.

This enables the support to be steered in a direction having a component up the slope of a laterally inclined mine working to correct for any slipping which may have taken place or would otherwise occur in a direction down the slope during advancement of the support.

Since each part of the structure A or B is overlapped longitudinally with the other such part, by virtue of the interleaved relationship, and each is associated with at least two longitudinally spaced props, angular movement of the part A can be effected reliably even under bad conditions of a roof and floor, that is to say when either of these is uneven or soft, due to the fact that whilst the angular movement takes place the inner part B is firmly secured by pressurisation of its associated props. Furthermore, the axis about which angular movement takes place is situated either in the region of the fixed guide elements W or between the two adjustable guide devices K, and the laterally directed forces of reaction applied against the fixed part B are lower than is the case where the two parts of the structure, which are required to be moved angularly relatively to each other, are offset longitudinally from each other.

The arrangement shown in FIGURE 1 may be used generally in the same manner as those illustrated in FIGURES 2 to 4, except that the part B will be subjected to some angular movement during its advancement in any case where the laterally shiftable element of the adjustable guide device K is set otherwise than in its medial position.

Referring now to the first embodiment of the support shown in FIGURES 5 to 7, this comprises a bottom structure which includes an outer base element formed of side members 10 each formed conveniently of two laterally spaced roof bars 11 of box-section secured to top and bottom plates 12 and 13 by welding, the top plates having secured thereto upstanding socket-like chambers 14 at the rearward end of the support and 15 at the forward end of the support. Chambers at corresponding ends are rigidly connected with each other by cross members 16 and 17, of which the former is a hollow upwardly extending fabricated structure forming a flushing shield for preventing or reducing the risk of loose material moving forwardly between the members 14 onto the base of the support from the rearward end of the latter. The members 16 and 17 may be welded to the chambers 14 and 15 respectively.

The outer base element, although rigid in the sense that the side members 10 are fixedly connected in each case to the cross members 16 and 17, does permit of some torsional and bending deflection within the range of its inherent elasticity to allow it to adapt itself to floor conditions, in particular uneveness in the floor. The rigidity, however, is sufficient to ensure proper operation of the guide devices and traction means as hereinafter described.

The bottom structure further includes an inner element 18 which is a fabricated structure of laterally spaced, upwardly extending, plates, there being two such outer plates 19 and two such inner plates 20 welded to top and bottom plates 21 and 22 to form two laterally spaced, approximately box-section, girders spanned at their rearward and forward ends by socket-like chambers 23 and 24, the bases of which are welded to the top plates 21.

The top structure comprises an outer part which in cludes side members 25 each formed of a pair of laterally spaced roof bars 26 of box-section, the vertical webs of which are somewhat inset from their upper and lower horizontal webs to provide flanges connected by plates 27 and 28. The side members 25 are rigidly connected with each other adjacent the rearward end of the support and at a position above the forward end of the bottom structure by cross members 29 and 30, the central portions of which are cranked or offset downwardly below the side members 25 to define in conjunction therewith a channel or passageway 31.

The top structure further comprises an inner part 32 similar in construction to the side members 25 and situated in this channel. The outer part and inner part of the top structure may be of the same, or approximately the same, length as seen particularly in FIGURE 5. In use the extent of forward projection of both the inner and outer parts of the top structure is such as to enable it to project forwardly to support the roof of a mine working over a conveyor 33 extending along the coal face of a long wall working and on to which coal is discharged from a coal-getting machine which travels along a guideway afforded by the side members of the conveyor.

The outer part of the top structure is supported by longitudinally spaced props 34 and 35 in the socket-like chambers 14 and 15 respectively of the outer base element. The inner part 32 of the top structure is supported by props 36 and 37 in the socket-like chambers 23 and 24. The chambers 14, 15, 23 and 24 thus form seatings in the bottom structure for reception of the props, and corresponding seatings at longitudinally spaced positions are provided for reception of the prop heads on both the inner and outer parts of the top structure, such as are seen at 32a for the inner part and 25a for the outer part of the top structure.

These props are hydraulic props which may be supplied with hydraulic fluid under pressure from a motor-driven pump or possibly from a manually or foot-operated pump.

Clearance spaces 38 exist between the side members of the outer base element and the inner base element and similar clearance spaces 39 exist between the inner part 32 and the side members 25 of the outer part of the top structure, so that intrinsically it is possible for relative angular movement to take place between the inner part of the support comprising the inner base element, its longitudinally spaced props, and the inner part of the top structure with respect to the outer part of the support, namely the outer base element, its longitudinally spaced props, and the outer part of the top structure.

To enable such movement to be effected when required guide means are provided to operate directly between the inner base element and the outer base element.

These guide means comprise two longitudinally spaced guide devices indicated generally at 40 and 41. The former include fixed guide elements 42 in the form of part cylindrical projections of strip metal secured to opposite side faces of the inner base element at the forward end of the latter and of such lateral projection as to span the clearance space in each case with, however, sutficient freedom to permit of angular movement about a vertical axis lying in a vertical transverse plane passing through the guide elements 42. Such axis would be situated, for example, in the region of the centreline of the prop 37.

The other guide device 41 is adjustable and includes a laterally shiftable guide element 44 in the form of a vertical plate movable in a transversely extending guideway 45 formed at the rear end of the inner base element. Lateral shift of the element 44 is effected by means of a piston and cylinder assembly having a piston rod 47 secured at opposite ends to brackets 46 on the chamber 23 and having its cylinder 48 connected by a pin 49 to a lever 50. The lever 50 can pivot about the vertical axis of a pin 51 mounted conveniently at the underside of the bottom wall of the chamber 23.

The guideway 45 is formed by a top plate 45a secured in any suitable manner, for example by bolts, to the rear walls of the chambers 14 with the intervention of a spacer member 45b to provide a downwardly presented transverse channel. The guideway is further formed by smaller plates 450 secured by bolts to lugs or brackets extending inwardly from the inner plates 20 of the boxsection girders which form the side members of the outer base elem ag in w th the ntervention of p g means to provide an upwardly presented channel in which the lower margin of the central portion of the plate 44 can slide. It will be noted that the plate 44 is cut away centrally in a direction upwardly from its lower edge to form a discharge outlet 44a of sufiicient width to communicate with the interiors of both of the box-section girders which form the side members of the outer base element to facilitate discharge of loose material from the interior of each of these members as hereinafter mentioned. The plate 44 has a slot 44b in its upper margin centrally in which the rearward end of lever 50 engages to enable such lever to shift the plate to the position required.

At its forward end the lever is associated with a retaining means comprising a plate 52 spanning the inner base element and secured at its opposite ends to the top plates 21, such plate having a plurality of apertures for the reception of pins. As shown two such apertures are provided one on each side of the central position of the lever 50 for reception of pins 53 to hold the lever in its medial position.

Upon displacement of the lever to one side or the other, one of these pins would also engage the inner edge face of the lever and would hence serve as a locking means to retain the lever in such position.

It will, of course, be understood that at least one of the pins 53 requires to be removed preparatory to operation of the guide device by the piston and cylinder assembly 47, 48 through the intermediary of the lever 50.

The piston and cylinder assembly may incorporate a single piston with piston rods projecting from opposite sides thereof and from each end of the cylinder as shown, or it may include two pistons one on each projecting piston-rod 47, and a valve system may be provided for supplying fluid to the cylinder so that the pistons are always moved in the same direction relative to the cylinder.

It will be noted that frictional forces in a direction longitudinally of the support and applied to the plate 44, in consequence of the engagement of its ends with the opposed inwardly presented side faces of the side members 10 of the outer base element, are borne entirely by the plate and the transverse guideway 45. The piston and cylinder assembly 47, 48 is isolated from these forces by the intermediary mechanism, that is to say the lever 50, and hence is not exposed to distortion or damage, even if loose floor or roof material should enter the clearance spaces 38 and cause a temporary obstruction.

For the clearance of such material the inner base element is formed with Ways for the discharge of such material rearwardly of the support. For this purpose each of the outer side plates 19 of the chambers of the inner base element is formed with an opening 54 adjacent to, but forwardly of, the plate 44 so that loose material can pass into the interiors of the chambers, which latter are open at their rearward ends.

As already mentioned the lower margin of the plate 44 is cut away to form an outlet 44a from the chambers for the discharge of the loose material.

The inner base element is operatively connected with the outer base element by a single hydraulic traction ram 55 having its cylinder 56 disposed between the side chambers of the inner base element and pivot-ally connected at 57 to a bracket on a rear plate of the inner base element. The piston rod 58 projects forwardl and is pivotally connected to a bracket 59 extending downwardly from, and secured to, the transverse member 17 at the forward end of the outer base element.

It will be noted that with this arrangement the traction ram is fully protected by virtue of its disposition within the inner base element when the latter is in its advanced position. It is at this stage when falls of roof material are rather more likely to take place. Further, the absence of any part of the ram projecting rearwardly from the inner base element minimises obstruction to the clearance of ny loo e material collecting in this region.

It will be noted that the length of the inner base element is approximately half the length of the outer base element and the former is capable of advancement by a distance which is slightly less than half the length of the outer base element. When so advanced the rear prop 36 will occupy a position just in the rear of the initial position occupied by the forward prop 37, and the latter will have moved into a position between the two props 35 at the forward end of the outer base element.

In order to guard against the possibility of undesired rearward shift of the inner base element, together with its props and associated part of the top structure, during advancement of the relatively heavier outer base element and props and its associated part of the top structure, tie means are provided to connect the inner base element to the conveyor 33. Such tie means comprise anchorage rods 60 which are slidable in the interiors of the chambers of the inner base element and at their forward ends are connected to each other by a cross member 61 having a bracket 62 inter-engaged with the conveyor. It will be noted that the bracket 62 affords a transverse guideway 63 in which a T section rail 64 on the conveyor is received so that translatory movement of the bracket along this guide rail is possible. At their rearward ends the anchorage rods 60 are provided with stop means in the form of downwardly cranked end portion 65. Alternatively collars or laterally projecting bolts or pins could be secured on these ends of the anchorage rods. The stop means co-operates with stop blocks (not shown) secured internally in each of the chambers adjacent to the forward end thereof positively to prevent withdrawal of the anchorage rods.

When the support is used in mine workings which present a slope laterally of the support, there is the possibility of the props 34 and 37 of the inner base element and the inner part of the top structure carried by these props becoming displaced towards the lower side of the working, such displacement being in the form of tilt so far as the props are concerned and translatory displacement with a slight degree of tilt so far as the inner part of the top structure is concerned. This could result in reduction in width of the clearance space between the inner part of the top structure and the side member of the outer part of the top structure on the lower side of the working, or in extreme cases contact between the inner part and this member thereby obstructing the establishment of any desired angular relation between the inner and outer base elements necessary to enable the support to be steered up the slope to correct any downward drift of the support as a whole.

To avoid or minimise this condition means are provided to counteract lateral tilt, if any, of the props 34 and 37. These means comprise a pair of deflector elements in the form of wedges 70 presenting vertical contact faces 71 which lie in planes oblique to the medial, longitudinally extending, reference axis 66 and have their rearward and outer extremities situated laterally outwardly of the forward path of movement of the adjacent side face of the chamber 24 at the forward end of the inner base element and their forward and inner extremities situated inwardly of this path so as to be engaged with the forward vertical corners of the chamber 24 intermediate these extremities during a terminal stage of the advancement step of the inner base element 18.

The Wedges 70 are preferably detachably mounted on respective chambers 15. This may be done, as seen in FIGURE 6a for example, by provision of brackets 72 Welded or bolted to the wedges 70 and brackets 73 welded or bolted to the chambers 15, each of these brackets being of angle form. The horizontal limbs 74 and 75 of th two brackets respectively are secured to each other by a clamping bolt 76. The clamping bolt may pass through a slot 77 extending in a direction laterally of the support through the limb 74 to permit the lateral position of the associated wedge 70 to be adjusted if required. Securement in any laterally adjusted position may be improved by the formation on the contacting faces of the limbs 74 and 75 of co-operative interfitting serrations 78 extending longitudinally of the support.

It will be understood that it is not essential in all cases to utilise two deflector elements. One only on the lower side of the inner base element may sufiice. Further, instead of providing for adjustment of the lateral position, wedge elements have different dimensions to provide for selective lateral positioning of the contact faces in a range of lateral positions may be employed if desired.

It is contemplated that deflector elements would be employed when the lateral slope of the mine working is such that a vertical line drawn from the combined centre of gravity of the props 34 and 37 and the inner part of the top structure carried thereby falls outside the lower side of the inner base element. Two deflector elements would normally be employed for floors in which the slope changes randomly from one direction to the other or for very soft to floors where the support as a whole may tilt laterally in one direction or th other randomly.

The props 36 and 37 carried by the inner base element, or at least one of them, may be made of larger effective diameter than the props 34 and 35 carried by the outer base element in order to ensure that the inner base element, its props, and inner part of the top structure will be established in firm roof supporting relation and can act as an abutment from which the requisite force can be exerted by the traction ram to advance the outer base element, its props and outer part of the top structure without rearward slipping of the inner base element. This may be contrived by providing a booster unit of larger effective diameter in which one or both of the props 36, 37 are seated at their lower ends. Such booster element may be as described and claimed in Patent No. 3,145,964. Alternatively or in addition hydraulic interlock means may be provided in the supply system operatively connecting the props 36 and 37 and the traction ram 55 with the pump to ensure that the last mentioned cannot be energized to advance the outer base element until the props 36, 37 are fully set or pressurised.

The operation of the support shown in FIGURES 5 to 7 is as follows.

Initially, preparatory to passage of the coal-getting machine along the coal face, the relatively movable parts of the support, herein for convenience called the inner part and the outer part, occupy the positions shown in FIGURES 5 and 6. As soon as the coal-getting machine has passed the support the newly exposed portion of the roof, resulting from removal of a layer of coal from the face, requires to be supported and such support is effected by advancement of the inner part of the support by appropriate pressurisation of the traction ram 55.

If at this stage it is necessary to effect correction of the lateral position of the support as a whole, due to a lateral slope of the mine working and previous downward drift of the support, two alternative procedures are possible.

Preparatory to advancement of the inner part the props 34 and 35 may be depressurised to release the outer parts 25 of the superstructure from load-bearing relation with the roof, the pin 53 on the higher side of the working is withdrawn and the piston and cylinder assembly 47, 48 pressurised to move the forward end of the lever 50 towards the higher side of the working and the rearward end of the lever and the plate 44 to the lower side of the working. The inner part of the support forms an abutment or anchorage and the lateral shift of the plate 44 will then move the outer part of the support angularly, so that the guide path defined by the inwardly presented sides of the side members 10 then face obliquely up the slope of the mine working.

The props 34 and 35 are then repressurised and the props 36 and 37 are depressurised.

The piston and cylinder assembly 47, 48 is repressurised to bring the lever back to the medial position shown and the removed pin 53 reinserted. The traction ram is then appropriately pressurised to advance the inner part of the support as already described.

As soon as the coal-getting machine has moved sufficiently along the conveyor (which is ordinarily formed of sections connected articulately to each other) to permit the particular section opposite the support concerned to be advanced towards the coal face, such advancement is carried out. For this purpose certain of the supports, for example one in every four along the row, is provided with a conveyor shifting hydraulic ram 90 which may conveniently be mounted on a bracket 91 on the outer base element at the outer side of one of the side members 10. The bracket 91 may have apertures 92 in the form of slots in which laterally projecting pins 93 from the ram extend to provide for freedom for the ram to pivot about the horizontal axis afforded by the pins 93. These latter may also have appreciable clearance with the apertures 92, thereby providing freedom for some angular movement of the ram 90 in a horizontal plane.

After advancement of the conveyor section concerned the outer part of the support is advanced, at which time the props 36 and 37 of the inner part are depressurised, the props 34 and 35 of the outer part are depressurised, and the traction ram 55 pressurised to draw up the cylinder 56 forwardly with respect to the piston rod 58.

Due to the oblique upward inclination of the guide path defined by the inwardly presented sides of the side members 10, both advancement of the inner part of the support and the outer part of the support will have taken place to some extent up the slope of the mine working. Advancement in this direction may be continued through as many cycles of advance as is necessary to correct any downward drift.

As a possible alternative, advancement of the inner part of the support may take place preparatory to any operation of the adjustable guide device 41, that is to say with the guide path parallel to the reference axis 66 extending medially and longitudinally of the support. This avoids the necessity of any depressurisation of the props 34, 35 before advancement of the inner part of the support.

Angular movement of the outer part of the support is then effected with the inner part in its advanced position in the manner already described, except that in this case the plate 44 would be left in its displaced position, that is towards the lower side of the working, whilst advancement of the outer unit is effected, so that the latter travels along an oblique upwardly extending path. In this case the removed pin 53 could be replaced to engage the inner edge of the forward end of the lever 50 and so avoid the necessity for continued pressurisation of the piston and the cylinder assembly 47, 48 during advance of the outer part of the support.

When sufiicient corrective movement in a direction up the slope of the mine working has been effected to compensate for any downward slippage, the adjustable guide device 41 can be operated to move the outer part of the support angularly back into parallel relation with the reference axis 66.

If, however, it is found in any particular site that there is a systematic drift down the slope of the working, all advancement may be effected along a path which inclines obliquely in an upward direction with respect to the slope of the mine working just sufiiciently to compensate for the downward slippage.

In certain cases where the downward slope of the mine working is not sufficiently severe to cause slippage of the base elements, it may nevertheless be sufiicient to result in downward lateral displacement of the inner part 32 of the top structure so that the clearance space 39 at the lower side of this part is reduced or contact is actually made at this side between the inner part 32 and the outer part 25 situated at the lower side of the working.

To compensate for this effect, if it occurs, the adjust able guide device 41 may be operated preparatory to advancement of the inner part of the superstructure and when the props 36 and 37 are depressurised to move the inner base element angularly in such direction as will compensate for the lateral displacement of the forward end of the inner part 32 of the top structure. The inner base element is then advanced in a direction parallel to the reference axis 66 but in an oblique attitude with respect thereto.

In comparison with the forms of guide means disclosed in my prior patents and co-pending applications previously mentioned, the present invention has the following advantages.

(1) The two parts of the support, and in particular the two base elements, are so designed that the inner base element is wholly overlapped longitudinally at all times by the outer base element. Consequently guidance of one base element by the other can be effected with out the necessity for resisting a turning moment increased intrinsically by the forward disposition of one base element relatvely to the other.

(2) The arrangement of the base elements permits very early advancement of a part of the top structure, namely that associated with the inner base element, to provide immediate support to a newly exposed portion of the roof, and concurrently efiects or sets up the requisite guidance path to compensate for any downward drift of the support as a whole due to a lateral slope on the mine working.

(3) In the specific form of the first embodiment the actuating piston and cylinder assembly for the adjustable guide device is eifectively isolated from frictional and other forces which could impose undesirable lateral stresses on the piston rods of such assembly.

(4) Effective guiding is attained by the use of only one adjustable guide device of simple and reliable design capable of being locked in any of it adjusted positions and hence rendered effective independently of the actuating piston and cylinder assembly.

{5) The support affords two laterally extending man- 'ways between the top structure and bottom structure, as indicated at and 81. The manway 81 is maintained at its full dimension longitudinally of the support at any stage of advancement of the inner base element between its rearward and forward limits of travel.

Referring now to the second embodiment illustrated in FIGURES 8 to 10, parts corresponding to those already described are designated by like numerals of reference with the prefix 1 and the preceding description is to be deemed to apply thereto.

In this embodiment the traction means comprises two hydraulic traction rams 155 whereof the piston rods 158 are pivotally connected at their forward ends by pins 159a to brackets 159 fixed to, and projecting laterally from, the forward ends of the side members of the outer base element.

The cylinders 156 of the traction rams are pivotally connected about vertical axes to a laterally shiftable element in the form of a bar 144 of an adjustable guide device 141. For this purpose the cylinders 156 have secured thereto upwardly extending blocks 156a carrying pins 15 6b for engagement through openings at the ends of the bar 144.

The bar 144 is slidable in a transverse guideway 145 on the inner base element formed between the rearward face 145a of chamber 124, and guide blocks 145b on the side chambers of the inner base element.

Transverse movement of the bar 144 is effected by a lever pivotally mounted on a pin 151 and capable of being locked in any of a number of positions by means of pins or bolts such as 153 extending through the lever and engaging in a selected one of openings 153a in a cross plate 152 secured between the side chambers of the inner base element.

The shorter forward arm of the lever has a slot 150a through which engages an upstanding pin 144a on the cross bar 144.

The lever may be operated manually to effect lateral movement of the cross bar 144, although a power energised actuating device such as a piston and cylinder assembly could be provided if desired.

Operation of the adjustable guide device 141 involving lateral shift of the bar 144 effects relative angular movement between the inner part of the support, namely the-inner base element, associated props, and inner part of the top structure on the one hand, and outer part of the support, namely the outer base element, associated props, and outer part of the top structure on the other hand, such angular movement being deter-mined and controlled by the adjustable guide device 141 and a fixed guide device 140.

The general manner of operation of the second embodiment of the support is as already described with respect to the first embodiment. In this case, however, it will be noted from the chain line positions of the rectangular structure comprising the cross bar 144, rams 155, brackets 159, and cross member 117 associated with the latter, that the line of thrust of the rams against the brackets is oblique to the reference axis 166. Consequently having set the inner and outer base elements in a particular angular relationship by means of the lever 150, the thrust of the rams tends to maintain this relationship.

FIGURE 8 shows in chain lines the position occupied by the inner part of the support upon advancement thereof, such inner part having been moved angularly by operation of the adjustable guide device.

Referring now to the third embodiment illustrated in FIGURES 11 to 15, parts corresponding to those already described with respect to the first embodiment are designated by numerals of reference with the prefix 2 and the preceding description is to be deemed to apply thereto.

In this embodiment the fixed guide device 240 and its fixed guide elements 242 are situated at the rearward end of the inner base element and the adjustable guide device 241 is disposed adjacent to the forward end. The adjustable guide device includes a laterally shiftable element in the form of a transverse plate 244 slidable in a transverse guideway 245 defined between the rearwardly presented face 245a of prop chamber 224 and an assem- -bly 245b mounted on, and extending between, the side chambers of the inner base element. The end portions 244]) of the plate 244 project downwardly into the clearance spaces 238 and the outwardly presented faces of these end portions are of curved convex form as seen in plan.

The assembly 245b comprises a cross member 2450 secured to the top plate-s 221 of the side chambers and provided centrally with forwardly projecting arms 245d slotted to receive a pin 2452 urged towards the plate 244 by a coiled compression spring 2451 disposed on a headed plunger 245g.

The plunger and spring bear against the pin 245e to urge same into a V-shaped slot 244s in the adjacent edge of the plate 244 centrally of its length, thereby acting as a biasing means tending to maintain the plate in its medial position.

For shifting the plate in opposite directions a piston and cylinder assembly is provided whereof the piston rods 247 projecting from opposite ends of the cylinder 248, are secured to brackets 246 mounted on the chamber 224. The cylinder 248 has a bolt or peg 248a entering an aperture in the plate 244.

,The piston and cylinder assembly 247, 248 may contain a single piston on a common piston rod or two pistons on individual piston rods respectively as already mentioned in respect of the first embodiment. This latter alternative is illustrated in FIGURE 17 wherein the pistons are indicated at 547a and the central web subdividing the cylinder at 548a.

A hydraulic ram for advancing the conveyor may be provided, as indicated at 209, at the outer side of one of the side members of the outer base element, such ram being mounted at its rearward end upon a bracket 208 projecting laterally from the side member concerned. The ram 209 may, as already indicated in the case of the first embodiment, be provided only on a fractional number of supports in a row, for example on very fourth support.

The manner of operation of the third embodiment is generally as already described with reference to the first embodiment. The displacement of the outer base element angularly is illustrated by the chain lines shown in FIG- URE 11.

Referring now to the fourth embodiment illustrated in FIGURE 15, parts corresponding to those already described in the first embodiment are designated by like numerals of reference with the prefix 3, and the preceding description is to be deemed to apply.

Inthis embodiment both the bottom structure and the top structure are provided with longitudinally spaced guide devices, one of which is fixed and the other adjustable. The fixed guide device may include fixed guide elements (not shown but similar to the guide elements 242) these extending laterally from the rear end of both the inner base element and the inner part of the top structure.

At a position immediately in the rear of the prop chamber 324 the inner base element is provided with an adjustable guide device 341 which is in conformity with that of the second embodiment and for this reason is not further described.

At a position vertically, or approximately vertically, above this adjustable guide device the top structure is provided with an adjustable guide device 341a.

This is of the same form as the device 341 except that the plate 344 has its ends 344k projecting upwardly into the clearance spaces 339 between the inner and outer parts of the top structure.

The manner of operation of this embodiment is as already described with reference to the first embodiment except that the adjustable guide device 341 would be operated concurrently, and in the same manner, as the adjustable guide device 341 operative between the inner and outer base elements.

Further, it will be noted that the resultant angular movement of one part of the top structure relative to the other is effected by direct operation of the two upper guide devices, namely the fixed guide device and the adjustable guide device 341, and does not involve the establishment of any pivotal axis by means of a prop head, so that the angular movement is not dependent upon the lateral stability of the props.

It will further be noted that the extent of upward projection of the end portions 3441; of the upper laterally shiftable plate 344 is sufficient to ensure that these remain in vertically overlapped relation with the opposed inwardly presented side faces of the outer parts 325 of the top structure when one of the parts of the top structure is lowered relatively to the other to bring it out of engagement with the roof. Further, the outer side faces of the end portions 34412 are of curved convex form, as seen in FIGURE 15, to avoid any obstruction to relative movement between these end portions and the outer parts of the top structure in the vertical direction, despite the presence of inwardly projecting flanges on the side members of the outer part of the top structure.

Referring now to the fifth embodiment illustrated in FIGURE 16, parts corresponding to those already described with reference to the first embodiment are designated by like numerals of reference with the prefix 4 and the preceding description is to be deemed to apply.

In this embodiment both the bottom structure and the top structure are provided with two longitudinally spaced adjustable guide devices. Those of the bottom structure are indicated generally at 4410 and 441d and 15 those of the top structure are indicated generally at 441e and 441 The form of these devices may be as already described in respect of the third and fourth embodiments, according to whether they are incorporated in the bottom structure of top structure.

The provision of two adjustable guide devices increases the angle through which relative angular movement can be effected between the inner and outer parts of the structure concerned for a given clearance space between them.

The manner of operation of the fifth embodiment is generally as already described in respect of the first embodiment, except that the laterally shiftable element in the guide device 441c would be displaced in a direction opposite to that in which the laterally shiftable element of the guide device 441d is displaced when effecting relative angular movement between the inner and outer base elements. The laterally shiftable element of the guide device 441e would be displaced in the same direction as that of 441a and the laterally shiftable element of the guide device 441 would be displaced in the same direction as that of the guide device 441d.

Referring to FIGURE 17, there is shown therein an alternative form of piston and cylinder assembly for actuating the laterally shiftable element of any of the foregoing adjustable guide devices.

In this arrangement the cylinder 548 is sub-divided internally by a web 548a to provide two separate cylinders 5481) in which operate separate pistons 547a carried on respective piston rods 547 projecting from opposite ends of the cylinder. The piston rods 547 may act upon a common laterally shiftable element 544, the cylinder 548 being fixed in the inner part of the structure B and the ends of the element 544 engaging the inwardly presented side faces of the side members of the outer part of the structure A.

Cylinder spaces to the left-hand sides of the pistons are connected to each other by a pipe 570, and cylinder spaces to the right-hand sides of the pistons are connected to each other by a pipe 571.

Selectively, by a valve means 572, fluid under pressure can be supplied from an inlet 573 connected to a source of hydraulic fluid under pressure to either pipe 570 or pipe 571.

One of the advantages of this arrangement is that for a given hydraulic pressure and cylinder diameter, the force exerted on the laterally shiftable element is materal- 1y increased (approximately double) in comparison with that obtainable by the use of a single piston on a common piston rod projecting from both ends of the cylinder. Alternatively, for a given force the diameter of the cylinder can be reduced resulting in an extremely compact unit.

The laterally shiftable element 544 can be guided in a guideway 545 extending laterally in the inner part B so that the piston and cylinder assembly is eifectively isolated from frictional forces attendant upon relative longitudinal sliding movement between the laterally shiftable element 544 and the upper part A of the structure.

Referring now to the sixth embodiment of the invention illustrated in FIGURES 18 and 19, parts corresponding to those already described in the first embodiment are designated by like numerals of reference with the prefix 6 and the preceding description is to be deemed to apply thereto.

This embodiment is similar to the second embodiment illustrated in FIGURES 8 to 10 in that hydraulic traction rams 655 are provided at the outer sides of the outer base element and their cylinders are coupled pivotally by pins 6561) to a cross bar 644 which is shiftable laterally through a guide member 64512 affording a transverse guideway 645 for the bar.

It will be noted that the cylinders 656 are spaced laterally from the side faces of the outer base element. Further, their piston rods 658 are universally connected to brackets 659 which are rigid with the side members 610 of the outer base element so that it is possible, by applying laterally directed force to the bar 644, to move this laterally to a limited extent whereby the thurst forces exerted by the piston rods 658 against their brackets are directed obliquely to the reference axis 666 and, therefore, provide a component of lateral thrust on the bracket 656, tending to move the outer base element angularly relatively to the inner base element about a fulcrum defined by the fixed guide elements 642 of the fixed guide device 640.

The rectangular structure formed by the bar 644, rams 655, brackets 659, and the cross member of the outer base element which effectively joins the brackets, namely 617, is functionally equivalent to the rectangular structure provided in the second embodiment, namely the cross bar 144, rams 155, brackets 159, and connecting member 117, except that in the present (sixth) embodiment the lever is omitted and initial adjustment of the position of the cross bar 644 requires to be performed manual- 1y, either by the application of force in a transverse direction directly to that bar, or possibly by the insertion of a tool such as a lever into the clearance space 638 between the inner and outer base elements. Once having set the inner and outer base elements in the required angular relation, this tends to be maintained in advancement of either part due to the oblique line of thrust of the traction rams.

A corresponding guide device is provided in association with the top structure. This comprises a pair of hydraulic traction rams of which one is seen at 680, these being situated at the outer sides of the outer part of the top structure.

The piston rods 682 are connected to the downwardly cranked cross member 629 and the cylinders are connected to a transverse bar 683 by means of pins 681b engaging in blocks on the cylinders. The bar is slidable transversely of the inner part of the top structure and serves, as in the case of the bottom structure, to transmit an advancement step thereto when required.

Referring now to the seventh embodiment illustrated in FIGURES 20 and 21, parts corresponding to those already described in the first embodiment are designated by like numerals of reference with the prefix 7 and the preceding description is to be deemed to apply thereto.

In this embodiment the inner base element is provided with an adjustable guide device 741 at its forward end. Such guide device comprises a longitudinally movable element 782 having laterally spaced guide rods 783 slidable in guideways afforded by the inner base element 718. Such guideways are of a sufficient width to permit of the guide rods being set parallel to the reference axis 766 or selectively to the left or to the right thereof, which last mentioned condition is shown in FIGURE 20. The longitudinally movable element 782 includes a cross member 784 connecting the guide rods at their forward ends and at this position includes centralising means in the form of cam elements 785 presenting contact faces 786 arranged obliquely to the reference axis 766 and crossing the respective paths of advancement of the forward inner corners 710a of the side members 710 of the outer base element.

At its forward end the longitudinally movable element 782 is also provided with means in the form of a bracket 787 enabling it to be connected to an anchor member such as a conveyor 733. The conveyor is provided with a rib 788 formed with a plurality of holes 789 through any one of which selectively a coupling pin provided on the bracket 787 can be passed.

At its rearward end the inner base element 718 has a fixed guide device 740 in the form of a transverse plate 742, at opposite ends of which engage the inwardly presented side faces of the members 710 to control the rela- 

